1. Field of the Invention
The present invention relates to printed wiring cards and more particularly to a tool useful for separating printed wiring circuit cards from printed wiring extender cards used during testing and maintenance procedures.
2. Background Art
Many operations, particularly those of telephone central office switching systems and similar computer controlled systems, utilize substantial numbers of printed wiring cards fitted into backplanes or card cage areas on a vertical basis. A number of these cards placed vertically on a side by side basis may equal 30, 40 or 50 or more cards. To perform maintenance or testing on these cards because of the presence of adjacent cards on either side of the card to be worked on is exceedingly difficult because of very tight clearances provided between adjacent cards.
To facilitate testing or maintenance, so-called "extender cards" are employed. In this manner, the card to be tested or worked on is removed from the card cage or backplane and an extender card is plugged into its place. The extender card then merely carries all of the appropriate connections to its rear where a separate connector is available and then the card to be worked on is then plugged into the rear portion of the connector at the back end of the extender card. In this way, the card to be worked on is readily available and is no longer located between two adjacent cards. The extender card is attached to the backplane and the card to be worked on is available with both sides open to a test or repair man wishing to work upon the card.
Printed wiring cards, particularly those employed in the telephone industry, usually have 330 or 440 pin connectors. When these cards are usually plugged directly into the card cage, ejector levers on the card are then used to unplug the card. However, when the card to be tested is plugged into an extender card, the combination of both of them being plugged into the card cage, the ejector levers are inoperative as far as the printed wiring card to be tested is concerned. In this arrangement the retention force of 330 or 440 pins is great enough to make the separation of the extender card from the other printed wiring card extremely difficult.
Usually by "sawing" (moving back and forth with a rocking motion) the card under test is worked out gradually. In this manner usually one side will come free before the other and the card then cocks at an angle stressing the extender card guide arms and perhaps damaging the power guide pins. The repetition of such action will eventually loosen or bend extender card guide arms as well as possibly damaging the electrical pins. Some maintenance personnel have found that cards can be separated using a tool such as a screwdriver or scissors to pry the cards apart. While preventing the kind of damage described above, particularly in reference to the power guide pins or the extender card guide arms, prying on the connector itself can damage or crack the housing and electrical pins may be momentarily shorted.
It is the object of the present invention to provide an appropriate tool to overcome the problems inherent in the prior art.